Lakeview Cabin III Edit
The Hammer can be found inside Cabin B. Enter the door on the right as you enter and you'll find it inside the Toolbox. Use this to nail down the boards in Cabin A to safely travel across or to smash the box outside the water closet to obtain the Flare Gun. The Wooden Box in Cabin A can also be smashed with this.
Last Christmas Edit
The hammer is found in the bathroom connected to the bedroom. The Wooden Box in the shed can be destroyed with the hammer and the shot gun shell can be smashed to blow out and kill a killer, or injure the player, whoever the red side is towards.